Weak-End Infeed Logic - ABB RELION 670 SERIES Applications Manual

Section 16
Scheme communication
16.7.2.2
772
CLOSED
Strong
source
A:1
A
CLOSED
A:2
ANSI99000043 V1 EN
Figure 376: Current distribution for a fault close to B side when all breakers are closed
CLOSED
Strong
source
A:1
A
CLOSED
A:2
ANSI99000044 V1 EN
Figure 377: Current distribution for a fault close to B side when breaker at B1 is
opened
When the breaker on the parallel line operates, the fault current on the healthy line is
reversed. The IED at B2 recognizes the fault in forward direction from reverse direction
before breaker operates. As IED at B2 already received permissive signal from A2 and
IED at B2 is now detecting the fault as forward fault, it will immediately trip breaker at B2.
To ensure that tripping at B2 should not occur, the permissive overreaching function at B2
needs to be blocked by IRVL till the received permissive signal from A2 is reset.
The IED at A2, where the forward direction element was initially activated, must reset
before the send signal is initiated from B2. The delayed reset of output signal IRVL also
ensures the send signal from IED B2 is held back till the forward direction element is reset
in IED A2.

Weak-end infeed logic

Figure 378 shows a typical system condition that can result in a missing operation. Note
that there is no fault current from node B. This causes that the IED at B cannot detect the
fault and trip the breaker in B. To cope with this situation, a selectable weak-end infeed
logic is provided for the permissive overreaching scheme.
CLOSED
FAULT
LINE 1
B:1
CLOSED
LINE 2
B:2
en99000043_ansi.vsd
FAULT OPEN
LINE 1
B:1
B
CLOSED
LINE 2
B:2
en99000044_ansi.vsd
1MRK 506 369-UUS -
Weak
source
B
Weak
source
Line distance protection REL670 2.2 ANSI
Application manual